When you access VDI Virtual Machine running on Windows XP and Windows 7, you will be able to get audio from the machine that you use to access but no microphone detected. Please refer to below figure (on the Recording tab):
By default, Windows 7 VM running in Hyper V does not have Sound driver. You will get audio redirection from the client computer. Same scenario happen to Windows XP Professional.
Now why still no microphone ?
Here is the finding that i would like to share:-
a) No Audio Redirection Recording for Windows XP VM. Please refer to statement mentioned in http://support.microsoft.com/kb/969084 .Even with RDC 7.0 install into the VM, this feature will not available to Windows XP VM as XP does not support audio recording redirection.
b) Audio Recording Redirection only available when virtual machine client operating system running on Windows 7 Enterprise / Ultimate/ Professional Edition.
c)By default, remote audio recording is disable on rdp file. Make sure you select "Record from this computer" or modify the rdp file to include
"audiocapturemode:i:1". You can put this value into RD Connection Broker server role under virtual desktop pool custom rdp setting as well.
To make life easier for the administrator, enable "Allow audio recording redirection" Group Policy setting. You can modify in
Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Device and Resource Redirection\Allow Audio recording redirection.
d) On the Windows 7 VM, modify the registry
fDisableAudioCapture REG_DWORD to 0. If you're running Windows Server 2008 R2 domain controller, you can use group policy to replace the registry value in Computer Configuration |Preferences | Windows Settings | Registry. (refer to below figure). For more detail, please refer to http://support.microsoft.com/?kbid=2020918
e) Enable Audio Recording redirection in RD Session Host Server.
At this moment, here is my test result after above configuration:-
Test result on 4th Sept 2010:-
a) Win7 to Win7 VM - Audio and Recording - Passed
b) WinXP with SP3 (install with RDC7) to Win7 VM - Audio and Recording - Passed
c) WinXP with SP3 (install with RDC7) to Win XP with SP3 (install with RDC7) - Audio Passed but Recording -fail to detect.
d) Win7 to WinXP with SP3(install with RDC7) - Audio Passed but Recording -fail to detect.
Here is some additional finding on connectivity and feature support: http://blogs.msdn.com/b/rds/archive/2009/08/21/remote-desktop-connection-7-for-windows-7-windows-xp-windows-vista.aspx
Will update again once i rerun multiple test. Stay Tuned.